IRC85 (Z39Ig/CRIg, co-receptor of VSIG4, V-set, Ig-domain-containing 4) consists a signal peptide, an extracellular domain having Ig domain, transmembrane domain, and intracellular domain (Langnasese K., Cloning of Z39Ig, a novel gene with immunoglobulin-like domains located on human chromosome X. Biochim Biophys Acta., pp. 1492-5225, 2000). IRC85 genes were expressed together with typical complement family in macrophages derived from monocytes as well as mainly the fetal tissues, adult lungs and placentas from human (Walker M G., Z39Ig is co-expressed with activated macrophage genes. Biochim Biophys Acta., pp. 1574-3879, 2002). It have been recently established that IRC85 is concerned in removing pathogens opsonized with C3 by phagocytosis, or in preventing the infection into another organ through binding with C3b or IC3b, a by-product of the complement C3 as the receptor of the complement C3 which is highly expressed on Kuffer cells in liver (Helmy K. Y., CRIg; a macrophage complement receptor required for phagocytosis of circulating pathogens, Cell, 124(5): pp. 915-27, 2006).
Therefore, the anti-IRC85 monoclonal antibody specifically binding to IRC85 could become the main target in developing the therapeutic agent to treat various bacterial diseases such as tuberculosis, enteritis disease etc caused by Tuberculosis, Tubercle bacillus, Yersinia, listeria, Salmonella, Shigella, Legionella, L. monocytogenes and the like (Melanie Hamon., Listeria monocytogens: a multifaceted model, Nature Reviews microbiology, pp. 423-434, 2006).
However, there has been not reported or disclosed on the separation of anti-IRC85 monoclonal antibody in any of the above cited literatures. Besides, there has been not reported or disclosed on the anti-bacteria activity of the anti-IRC85 monoclonal antibody against the bacteria infection into cells in any of the above cited literatures.
Therefore, the present inventors have prepared 6H8 hybridoma cell producing novel anti-IRC85 monoclonal antibody specifically binding with IRC85 and found that the antibody showed potent effect in removing the infected/phagocytosed bacteria from THP-1, a monocytic cell that expresses human IRC85 and is infected with Listeria monocytogenes or MDR-tubercle bacillus to complete the present invention. These and other objects of the present invention will become apparent from the detailed disclosure of the present invention provided hereinafter.